<%if (css === 'less') {-%>
  @max-size: 30;
  @min-size: 12;
  
  .font-size(@i) when (@i <= @max-size) and (@i >= @min-size) {
    .fs-@{i} {
      font-size: @i * 1px;
    }
  
    .font-size(@i - 2);
  }
  
  .font-size(@max-size);
  
  <%} else if (css === 'scss') { -%>
  $font-size: 50;
  
  @for $size from 0 through $font-size {
    @if $size % 2 == 0 and $size >= 10 {
      .fs-#{$size} {
        font-size: $size * 1px;
      }
    }
  }
  <%}-%>
  